1979: North Korea starts to build a 5 MWe (30 MWt) reactor at Yongbyon
that can produce approximately enough plutonium for one bomb a year.

1985: North Korea signs the Nuclear Nonproliferation Treaty (NPT), promising
not to produce a bomb and to open all nuclear sites to inspection. In
return, the Soviets promise North Korea several large power reactors.

1985: North Korea starts to build a 50-MWe (200-MWt) reactor that can
produce enough plutonium for seven to ten bombs a year. It also starts
to build a large plant to process plutonium into weapon-ready form.

1986: The 5 MWe (30 MWt) reactor begins to produce plutonium.

July 1987: North Korea misses the first 18-month deadline for the beginning
of international inspections. Inspectors grant an 18-month extension.

December 1988: North Korea misses a second deadline for beginning international
inspections, and demands "legal assurances" that the U.S. won't
threaten it with nuclear weapons.

1989: According to the Central Intelligence Agency (CIA), North Korea
secretly unloads enough plutonium-bearing fuel from its 5 MWe (30 MWt)
reactor to make one or two nuclear bombs.

1989: North Korea begins to process plutonium into nuclear-ready form.

September 1989: North Korea starts to build a 200-MWe (800-MWt) reactor
that can produce enough plutonium for 30 to 40 bombs a year.

February 1990: North Korea threatens to drop out of the NPT unless the
U.S. removes all nuclear weapons from the peninsula.

March 1990: U.S. fines German firm Degussa for illegally supplying U.S.-origin
reactor material to North Korea.

November 1990: North Korea tries to buy electronic components for bomb
triggers from a U.S. company.

December 1990: South Korean press reports 70 to 80 high-explosive tests
of bomb components in North Korea.

1990: North Korea tests its large plutonium processing plant, showing
it is operational.

1990: North Korea starts up its new plant to process uranium for reactor
fuel.

1990: A KGB report asserts that North Korea has developed a nuclear
device, but has decided not to test the device in order to avoid international
detection.

October 1991: U.S. begins to remove nuclear weapons from South Korea.

December 1991: North and South Korea agree to denuclearize the peninsula
and not to produce, test, receive, deploy or possess nuclear weapon fuel
or weapons, or the means to make them.

January 1992: North Korea agrees to regular IAEA inspections of its
nuclear facilities.

Late 1992: The IAEA finds evidence that North Korea had processed more
than the 80 grams of plutonium it had disclosed to the Agency.

1992: According to U.S. intelligence, North Korea buries the first floor
of a two-story building believed to contain waste from plutonium extraction.

1993: U.S. aerial photographs and IAEA chemical analysis data confirm
existence of a nuclear waste dump and inconsistencies in North Korea's
declaration of nuclear materials.

February 1993: IAEA inspectors ask to see two undeclared sites, on suspicion
that secret plutonium processing will be revealed, and allow one month
for compliance.

March 1993: North Korea rejects the request and announces its intention
to withdraw from the NPT.

April 1993: The IAEA declares North Korea in non-compliance, and refers
the matter to the U.N. Security Council.

June 1993: North Korea "suspends" its withdrawal from the
NPT but continues to bar inspectors from full inspection.

August 1993: IAEA inspectors are restricted to working at night by flashlight.

October 1993: North Korea repudiates the NPT and breaks off talks with
inspectors.

November 1993: North Korea breaks off denuclearization talks with South
Korea.

November 1993: A North Korean diplomat is expelled from Moscow for trying
to hire Russian scientists.

December 1993: North Korea offers to let inspectors into only five of
seven declared sites, barring them from the 5MWe (30-MWt) reactor, the
plutonium processing plant and two undeclared sites. Inspectors say their
cameras no longer work.

December 1993: U.S. intelligence says North Korea has a "better
than even" chance of possessing one or two bombs.

December 1993: The IAEA indicates it can no longer provide any meaningful
assurance on the peaceful use of North Korea’s declared nuclear
installations.

1993: North Korea manufactures fuel for its 50-MWe (200-MWt) reactor.

January 1994: North Korea agrees to a one-time inspection of all seven
declared sites, but balks at procedures.

February 1994: North Korea agrees to inspection procedures but delays
inspectors' visas and continues to bar inspectors from undeclared sites.

March 1994: IAEA inspectors find evidence that North Korea is constructing
a second plutonium processing line, which would double plutonium production.

May 1994: North Korea shuts down its 5 MWe (30 MWt) reactor and removes
about 8,000 fuel rods, which could be reprocessed into enough plutonium
for 4-5 nuclear weapons. The IAEA is denied permission to inspect the
removed fuel rods.

June 1994: The IAEA adopts a resolution concluding that North Korea
is “continuing to widen its non-compliance… by taking actions
which prevent the Agency from verifying the history of the reactor core
and from ascertaining whether nuclear material from the reactor had been
diverted.” Additionally, the IAEA suspends all non-medical technical
assistance to North Korea.

June 1994: North Korea withdraws its membership from the IAEA.

October 1994: U.S. and North Korea conclude an "Agreed Framework," under
which North Korea will freeze and eventually dismantle its graphite-moderated
reactors and related facilities, and will safely store spent fuel from
the 5MWe (30 MWt) reactor. In exchange, the U.S. agrees to organize a
consortium that will provide North Korea with light-water reactors and
will make arrangements to provide heavy heating oil during construction
of the light-water facilities.

1994: IAEA inspectors confirm North Korea has frozen its nuclear program
and stopped construction on the unfinished reactors.

1995: U.S., Japan and South Korea establish the KEDO consortium, which
will provide North Korea with two South Korean-manufactured light-water
reactors, worth $4.6 billion, financed primarily by South Korea and Japan.

April 1996: North Korea announces it will no longer respect the demilitarized
zone and sends troops into the zone for three days.

September 1996: A North Korean submarine, believed to be spying, runs
aground off the coast of South Korea. South Korea kills seven suspected
crewmen.

October 1996: In response to the submarine incident, South Korea delays
progress on the Agreed Framework. China joins the U.N. Security Council
in criticizing North Korea and expressing "serious concern" about
the incident.

December 1996: North Korea apologizes to South Korea for the September
submarine incident, and promises to prevent the recurrence of similar
incidents in the future.

December 1996: North Korea agrees to face-to-face talks with South Korea
and the United States on the possibility of negotiating a formal end
to the Korean War.

1997: Top North Korean theoretician and close adviser to Kim Jong Il
defects to South Korea.

August 1997: Construction begins on two light-water nuclear reactors
being built in North Korea as part of the 1994 Agreed Framework with
the United States.

July 1998: The U.S. General Accounting Office (GAO) reports that North
Korea is refusing to allow IAEA inspectors full access to its nuclear
sites.

March 1999: A U.S. Department of Energy intelligence report allegedly
claims that North Korea is working on uranium enrichment techniques.

May 1999: A team of American nuclear specialists arrives in North Korea
to begin an inspection of what is suspected of being an underground nuclear
weapons site at Kumchangri. No evidence of nuclear activity is found.

July 1999: A U.S. intelligence report claims that North Korea has between
25 and 30 kilograms of weapon-grade plutonium, enough to make several
nuclear warheads.

May 2000: A second team of U.S. inspectors visits the Kumchangri underground
facility, and again finds no evidence of nuclear activity.

October 2000: The CIA assesses that North Korea has processed enough
plutonium for at least one, and possibly two, nuclear weapons.

May 2001: North Korea threatens to pull out of the 1994 Agreed Framework,
saying the United States has failed to live up to its obligations under
the agreement.

June 2001: The IAEA says it is unable to verify that North Korea is
not diverting nuclear material for military purposes, as North Korea
has not provided inspectors with sufficient access.

September 2001: KEDO begins excavation work for the first light-water
reactor.

March 2002: President Bush decides not to certify North Korea’s
compliance with the 1994 Agreed Framework before sending fuel oil to
Pyongyang, indicating the United States does not have enough information
to determine whether North Korea is complying with the agreement. He
decides, however, to grant a waiver, allowing the fuel oil shipments
to continue.

October 2002: The United States claims that North Korea acknowledged
to a U.S. delegation headed by Assistant Secretary of State James A.
Kelly that North Korea has been secretly enriching uranium. The admission
was prompted by U.S. intelligence indicating North Korea was trying to
acquire large amounts of high-strength aluminum, which can be used in
equipment to enrich uranium.

October 2002: U.S. intelligence reportedly concludes that Pakistan was
a major supplier of critical equipment to North Korea’s newly-revealed
enrichment program.

November 2002: KEDO decides to suspend heavy fuel oil shipments to North
Korea until North Korea takes steps to dismantle its nuclear program.

December 2002: North Korea reportedly succeeds in purchasing from a
Chinese company 20 tons of tributyl phosphate (TBP), which can be used
to extract plutonium from spent reactor fuel.

December 2002: The IAEA announces North Korea moved 1,000 fresh nuclear
fuel rods to a storage facility at the Yongbyon reactor site.

December 2002: North Korea decides to lift the freeze on its nuclear
facilities and orders IAEA inspectors to leave the country.

January 2003: North Korea announces it is pulling out of the NPT and
rebuffs demands that it allow a return of U.N. inspectors.

January 2003: U.S. spy satellites see trucks in North Korea that appear
to be moving the 8,000 spent fuel rods from storage.

February 2003: North Korea announces it has restarted its nuclear facilities.

February 2003: The IAEA declares North Korea in non-compliance with
its inspection
obligations and sends the issue to the U.N. Security Council.

February 2003: U.S. spy satellites show a steady stream of activity
around North Korea’s plutonium reprocessing plant. The activity
indicates preparation to activate the facility.

April 2003: During talks in Beijing among the United States, North Korea
and China, a North Korean official says North Korea has nuclear weapons.

April 2003: North Korea threatens to “transfer” or “demonstrate” its
nuclear weapons during the Six Party Talks in Beijing, according to an
unclassified CIA report to Congress.

May 2003: A South Korean official says the United States has a satellite
photo showing smoke coming from radiation and chemical labs at Yongbyon
(signaling the site may be reprocessing spent fuel rods).

May 2003: North Korea nullifies a 1992 agreement with South Korea to
keep the peninsula free of nuclear weapons.

June 2003: North Korea announces its intentions of building nuclear
weapons in an attempt to decrease the size of its conventional military
forces.

June 2003: The CIA reportedly believes that North Korea is developing
technology to make nuclear warheads small enough to fit on missiles.

July 2003: The United States reportedly believes North Korea has begun
to process spent fuel rods.

July 2003: South Korean news indicates North Korea claimed to have restarted
the 5 MWe (30 MWt) reactor at Yongbyon, as well as to have resumed construction
on two other reactors frozen under the 1994 Agreed Framework.

July 2003: North Korean officials say they have finished producing enough
plutonium from the 8,000 spent fuel rods for six bombs, which they intend
to weaponize quickly.

July 2003: South Korean intelligence confirms North Korea has performed
70 high explosives tests.

August 2003: North Korea repeats its April 2003 threat to “transfer” or “demonstrate” its
nuclear weapons during Six Party Talks in Beijing, according to an unclassified
CIA report to Congress.

September 2003: Chinese authorities at the China-North Korea border
stop a shipment of chemicals that could have been used in North Korea’s
nuclear program, according to an unclassified CIA report.

October 2003: North Korea confirms that in June 2003 it completed reprocessing
all of the 8,000 spent fuel rods previously under IAEA safeguards, and
announces that all of the plutonium thus derived was being used to increase
the size of North Korea’s nuclear deterrent force.

October 2003: New intelligence reportedly estimates that North Korea
may have produced one, two, or more new nuclear weapons in recent months.

October 2003: A German national is charged with exporting aluminum tubing
for North Korea’s uranium enrichment program.

November 2003: The CIA tells Congress that it believes that North Korea
is able to turn nuclear fuel into functioning weapons without performing
a full nuclear test.

November 2003: The United States and its allies announce that beginning
December 1, they will suspend all work for one year on a nuclear power
project in North Korea that was part of the 1994 Agreed Framework.

January 2004: A U.S. delegation spends a day at the Yongbyon nuclear
complex, where it is shown what North Korea claims is weapons-grade plutonium.
A member of the delegation indicates the cooling pond there is empty.

March 2004: A CIA classified intelligence report reportedly concludes
that North Korea probably received from Pakistan’s Khan Research
Laboratories a comprehensive nuclear package, similar to that received
by Libya, which included all the equipment and technology it needed to
produce uranium-based nuclear weapons.

April 2004: Pakistani nuclear scientist Abdul Qadeer Khan is reported
to have told investigators that during a 1999 trip to North Korea, he
was shown three nuclear devices. It is unclear whether he would have
had the expertise to distinguish between an actual weapon and a mock-up.

April 2004: U.S. intelligence prepares to revise its estimate of the
number of nuclear weapons possessed by North Korea from "possibly
two" to at least eight.

June 2004: North Korea includes a ban on nuclear transfers in a nuclear
freeze proposal it puts forward at the third round of the Six Party Talks,
according to an unclassified CIA report.

February 2005: North Korea announces that it has “manufactured” nuclear
weapons and indefinitely suspends its participation in the Six Party
Talks.

April 2005: North Korea reportedly shuts down the 5 MWe (30 MWt) reactor
at its Yongbyon nuclear complex.

October 2006: North Korea announces that it intends to conduct its first
nuclear test explosion.

October 2006: North Korea conducts its first nuclear test. U.S. intelligence
confirms that an underground nuclear explosion of less than one kiloton
occurred on October 9 near P’unggye, North Korea.

October 2006: The U.N. Security Council unanimously passes a resolution
condemning North Korea’s nuclear test and imposing a range of sanctions.

October 2006: After analyzing atmospheric sampling data, U.S. intelligence
agencies reportedly conclude that the nuclear explosive device tested
by North Korea on October 9 was plutonium-based.